If this is something you just want to do once, you can simply use the 1024 control panel example to read tag A, make note of the tag ID and protocol, and manually write it to tag B.

If this is something you want to do over and over, you just need to make a program that will read in and remember tag A's ID, and then write it to another tag when it comes in range or when you push a button. For sample code on how to read and write, see the download section for your programming language.